The proclivity of people of our generation, and our time period to put the things spoken of 2,000 years ago into our accustomed thinking, and our accustomed life style is anachronistic. "All the world" 2,000 years ago was not the same world that we live in today. Let me offer a previous post from my site that addresses this use of "all the world" of Matt. 24:14.
When it comes to reading the Bible, the western English speaking world is at a great disadvantage. We have been trained to take things at face value, and to be very literal minded. But, the peoples of the Eastern world have a much different mindset, and are very familiar with poetical language, metaphorical prophesy, and the huge imagery of hyperbole to make a point.
Luke 2:1 -
"And it came to pass in those days, that there went out a decree from Caesar Augustus that all the world should be taxed." (KJV)
"And it came to pass in those days, there went forth a decree from Caesar Augustus, that all the world be enrolled --" (YLT)
"In those days a decree went out from Caesar Augustus that all the world should be registered." (ESV)
"In those days Caesar Augustus issued a decree that a census should be taken of the entire Roman world." (NIV)
"And it came about at that time that a dvar malchut (decree) was sent out from Caesar Augustus to register everyone in the entire Roman Empire." (Orthodox Jewish Bible)
It only makes sense, and we subconsciously recognize that Caesar Augustus only had authority and dominion to tax the people living in the lands which he ruled... the Roman empire. So, "all the world" in Luke 2:1 equaled the old Roman empire.
Then, which "world" did Christ speak of in Matt. 24:14?
"And this gospel of the kingdom shall be preached in all the world for a witness unto all nations; and then shall the end come." (*KJV)
Did Christ mean in every land across the entire physical earth? Or, did He mean the Roman empire of that time period?
The word used for "world" in Matt. 24:14 is Strong's Greek 3625: "oikoumené: the inhabited earth" and the definition is:
"(properly: the land that is being inhabited, the land in a state of habitation), the inhabited world, that is, the Roman world, for all outside it was regarded as of no account." (SeeBibleHub)
"Oikoumené" was used in two other verses:
"Men's hearts failing them for fear, and for looking after those things which are coming on the earth [oikoumené]: for the powers of heaven shall be shaken." (KJV)
Remembering that when God's prophesy speaks of heavens that can be shaken it is a metaphor for the kingdoms of men. (See my other post "Heaven and Earth Have Passed Away.) The heaven where God sits on His throne cannot be shaken or removed.
Therefore, the heaven, or kingdom referred to in Luke 21:26 was that which ruled the earth in the first century A.D. and was the Roman empire.
The second use of "oikoumené" is found in Acts 19:27.
"So that not only this our craft is in danger to be set at nought; but also that the temple of the great goddess Diana should be despised, and her magnificence should be destroyed, whom all Asia and the world [oikoumené] worshippeth." (KJV)
The "world" here referred to all the lands that worshipped the pagan goddess Diana, which at that time was Asia and the surrounding pagan nations. Ellicott's Commentary defines it.
"Asia is, of course, the proconsular province, and the “world” is used conventionally, as in Luke 2:1, for the Roman empire. Apuleius uses language almost identical with that of Demetrius, “Diana Ephesia cujus nomen unicum . . . totus veneratur orbis.” Source:here.
So, the pagan nation(s) which worshiped the goddess Diana was one of the provinces of the Roman empire. A nation ... a province of Rome. Because, Rome acquired more territories as it conquered a people who occupied a certain land or nation, and then added those nations to their empire as a province of Rome.
The Romans distinguished Republican provinces which were controlled by the Senate, and the Imperial provinces which were ruled by representatives of Caesar who answered only to Caesar. A list of the Roman provinces in 14 AD is available at Livius.org, and included Sicilia, Germania, Hispania, Africa, Asia, Macedonia, Gallia, Syria, Cyprus, and Judea.
The Romans kept conquering nations throughout the first century AD and by the time Revelation was written in 66-68 AD had added Mauretaina, Britannia, Thracia, the Alps of Italy, Switzerland, and France.
The world and the nations of the world during the time in which the books of the New Testament were written was the old Roman empire.
Therefore, Christ's prophesy in Matthew 24:14 can be paraphrased for our understanding as follows:
"And this gospel of the kingdom shall be preached in [in all of the Roman empire] for a witness unto [all the people who inhabit the Roman provinces]; and then shall the end come."
The Bible was not written in English, and the New Testament was not written yesterday. When reading the Bible we have to put ourselves in their shoes, and their time period, their age, their political world, and their culture.
Paul stated in Col. 1:23,
"If ye continue in the faith grounded and settled, and be not moved away from the hope of the gospel, which ye have heard, and which was preached to every creature which is under heaven; whereof I Paul am made a minister;" (KJV)
"Every creature which is under heaven" was every person under the rule of the "heaven" of the earthly kingdom of the Roman empire. As the book of Colossians was written about 61-62 AD (see DatingTheNewTestament), then according to Paul, the gospel had been preached in all the "world" throughout the Roman empire by 61 - 62 AD.
The "end" came approximately 8 years later in 70 AD at the destruction of the old covenant temple in Jerusalem. And "all the world" saw it (Rev. 1:7).
"Because thou hast kept the word of my patience, I also will keep thee from the hour of temptation, which shall come upon all the world [oikoumenēs], to try them that dwell upon the earth [land]." (KJV)
"And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world [oikoumenēn]: he was cast out into the earth, and his angels were cast out with him." (KJV)
"For they are the spirits of devils, working miracles, which go forth unto the kings of the earth [oikoumenēs] and of the whole world [oikoumenēs], to gather them to the battle of that great day of God Almighty." (KJV- literally "kings of the inhabited whole")
In each of these verses above " oikoumenēs" or " oikoumenēn " is the same meaning of the known world of their day. That world was the inhabited lands and provinces of the Roman empire. Their world was the fourth beast kingdom that had been prophesied from Daniel chap. 7 in which Christ was manifested and appeared on earth to become the lamb slain from the foundation of the "kosmou" [world or universe - Rev. 13:8].
It was not used in these scriptures to mean the entire earth. The prophesies of Matt. 24 and of Revelation had an application to the first century AD and to the known world of its day - the old Roman empire... the world in which they lived. Taking them out of the 1st century A.D. is anachronistic.
We must search the original scriptures and become familiar with the Hebrew Aramaic definitions, and idioms in order to fully comprehend their meanings. The word "world" had been used in the English translations of the scriptures for several different meanings, and we cannot apply it the same way each time. It does not always mean the entire earth. Source: Frequent Mistakes Part IV
Nor does "the end" refer to the end of all life on earth. It was the end of days of the prophesy Grabriel had given to Daniel in Dan. 9:24 - 12:13, which was solely about Daniel's people - thy people - and about Daniel's holy city - thy holy city: the Jews and Jerusalem. The end was of the end of the desolations of Jerusalem, and the destruction of that 2nd Mosaic temple and all of the animal sin sacrifices that became profane once Christ was sacrificed on the cross.
The gospel of Christ has been in effect since the first century A.D. when Christ roared those words forth from Jerusalem / Zion (Joel 3:16; Amos 1:2). They have been roaring throughout the centuries and throughout all the nations ever since. They are very much still in effect.
See my other posts for Daniel and The End Times, Frequent Mistakes - Part III: The Last Day, and others at ShreddingTheVeil